Research On Energy Optimization Of Wind Generation System

The wind generation technology has gained much attention all over the worldbecause of the global energy shortage and the environmental protection require-ments. However, due to the multi-variable and highly coupled nona?aine structure,high-performance control of the variable-speed variable-pitch wind generation system(VSVP-WGS) becomes a challenging problem. Conventional researches on the energyoptimization of the wind generation system focus on the e?ciency and reliability ofthe single set system in di?erent wind speed regions. However, along with the increaseof the wind power capacity in a power grid, more requirements have been proposedfor the safety operation of the grid, such as enough power supply in dynamic state andsmooth power injection in steady state from the VSVP-WGS. All the contents havebeen today's key issues for the energy optimization of the VSVP-WGS. In this disser-tation, the controls of the dynamic energy capture and the steady output power levelwere systematically investigated. The main works and innovative contributions of thisdissertation are as follows.1. The maximal power point tracking (MPPT) strategy taking the wind turbines'dynamics into account was proposed. Conventional strategies of the maximal powerpoint tracking control are based on the steady optimization algorithm, and do not con-sider the turbine dynamics. With the feedback linearization theory, the control of theactive and reactive power of the generator is discoupled. And with a"zero-observer",the dynamic power of the wind generation system is observed indirectly, which is usedfor the dynamic compensation of MPPT. As the results, the e?ciency and the dynamicpower supply capability of the wind generator system are improved.2. The inverse-system pitch control strategy is proposed for the output power levelcontrol of the VSVP-WGS. Based on the inverse-system theory, a nonlinear pitch con-troller is designed for the control of the nona?ne wind generation system. Comparedwith the classical linear controller, this nonlinear one reserves the capabilities of the simple implementation. Moreover, the controller keeps not only stable and rapid re-sponse in a large wind speed region but also robustness to the small disturbance of thewind turbine parameters.3. The inverse-system based robust pitch control strategy is proposed for the out-put power level control of the VSVP-WGS. The strategy combines the inverse-systemand robust compensation method. Compared with the inverse-system pitch controlstrategy, it can keep not only the output power level of the VSVP-WGS but also robust-ness to the large scaled disturbances of the wind turbine parameters and other boundeduncertainties.4. The performances of the nonlinear control methods mentioned above for theenergy optimization of the VSVP-WGS are verified by the simulations and experimentsbased on a hardware-in-loop platform of the VSVP-WGS which is partly establishedby the author.